If you're "quantified" on Quantcast, it should be pretty spot on to Google Analytics since it's direct measurement. If you're not, then it's definitely going t

If you're "quantified" on Quantcast, it should be pretty spot on to Google Analytics since it's direct measurement. If you're not, then it's definitely going to be off like Compete. I use Compete stats as relative measurements against other websites (assuming everyone's off by a similar ratio). I use Quantcast stats to look at the demo info.